Photometer.



No. 884,835. PATENTED APR. l4, 1908.

J. P. MEYER.

PHOTOMETE'R.

APPLICATION FILED MAY 31, 1907.

awue'ntoz q vi/liweowo shutter as shown, consists of two plates JOSEPH P. MEYER, OF ROCHESTER, NEW YORK. V

PHOTOMETER.

Specification of Letters Patent.

Patented April 14, 1908.

Application filed may 31, 1907f Serial No. 878,661.

To all whom it may concern:

Be it known that I, JOSEPH P. MEYER, a citizen of the United States, and resident of Rochester, Monroe county, State of New York, have invented certain new and useful Improvements in Photometers, of which the I following is a specification.

This invention relates to a device for measuring light and determining automatically the proper length of time toexpose a photographic plate or film.

As is well known to photographers, the light varies continuously in certain kinds of weather and in order to secure the best re sults it is necessary to know the intensity of the light at the moment of ex osure.

Accordin to my invention measure .the reflected ligit from the object to be photographed, and the time of exposure thus determined depends upon the nature of the obl'ect or scene as wel as the intensity of the ight to which it is exposed.

The nature of the invention will be more fully understood from the followingdetailed description in connection with the accompanying drawin in which,

Figure 1 is a p an view of a device embodying the invention; Fig. 2 is a lon itudinal section on the line 22 of Fig. 1; i 's. 3, 4 and 5 are sections on the line 3-3 of Fig. 2 showing the valve or shutter in different positions; F ig. 6 is a section on the line 6-6 of Fig. 2; Fig. 7 is a detail of the shutter opening device.

Referring to the drawing, 1 indicates a metal tube and 2 any suitable eye piece. Within the tube near the eye, piece or sighting end of the tube is a transversely arranged disk 3 of colored trans arent material, such for instance, as ruby ass or celluloid. At or near the forward or ight inlet end 4 of the tube there is a shutter adapted to shut out more or less of the light from the tube. This 5, 6, pivoted at 7 to a bracket 8 which is carried onthe outside of the tube. The springs 18 tend constantly to close the shutter, that is, to throw the plates 5, 6, into the position shown in Fig. 3. A wedge 9 arranged within the tube is adaptedto be projected between the plates of the shutter to move them apart and admit more or less light to the tube. As shown, the wedge is in the form of a slide having a connection through a slot 10 with a handle or knob 11, by means of which the wedge may be moved. A pointer 12 connected with the knob 11 indicates on a scale 13 the degree of opening of the shutter or the li roportion of light admitted by the shutter. he fi ures on the scale are preferably made to in icate the actual time which a plate should be ex osed, As shown, the shutter is located slig tly back from the forward end of the tube and the blades of the shutter work in transverse slits in the tube.

- Between the shutter and the eye piece, and at some distance from the shutter, I place a transverse disk 14 of translucent or semiop'aquematerial, such as parchment or light brown paper or ground glass and on this disk I place an opa ue mark 15, preferably a black diametrica line.

The operation of the device is as follows: The instrument should be directed to the object or scene to be hotographed. If the shutter be open and t 1e eye piece be placed to the eye so as to practicall exclude light from that end of the tube, tl ie dark line or mark 15 will be seen very distinctly excepting in very dark weather. If the line or mark appear faintly with the shutter wide open "the exposure should be equal to the maximum indicated on the scale. If, how ever, the mark 15 is distinctly visible, the wedge should be withdrawn and the shutter permitted to close gradually until the mark is barely visible. I The device may be operated in the reverse manner by starting with the shutter closed and. gradually opening it until the mark can be seen faintly. In either case when the mark is faintly visible the cate the proper exposure on the scale 15.

It will be. understood that the device described is merely one embodiment of my invention and that various changes in the form and arrangement of the parts and in the materials used. and scope thereof. For instance, the tube and eye piece may be of any suitable opaque material and the .tube or casing may be of rectangular or other cross section. The diaphragm at the'eye piece may be glass, celluloid or other transparent material of any suitable color. The disk 14 may be of aper, celluloid, ground glass or other trans ucent or semi-opaque material through which a certain proportion of light can pass and the index 12 will indi- I may be made within the spirit mark may be of different designs. The shutbeing simply necessary to provide a shutter ..closing the shutter to any and a translucent diaphragm having an ent is,

' graphic exposures, the combination of- .a tube to work very satisfactorily. While I prefer the construct on lllustrated "I may in some instances combine the transarent colored diaphragm with the transucent diaphragm 0r omit the colored dia phragm and modify the translucent diaphragm accordingly.

Having described my invention what I claim and desire to secure by Letters-Pat- 1. In a "device for determining photoor casing, a transparent diaphragm at the sighting end thereof, a shutter at the light in ct end thereof, means for o crating the shutter, and a translucent diap agm intermediate theends of the casing and having a mark thereon, for the purpose set forth.

2. In a device for determiningh photographic exposures, a tube or casing avin a transparent colored diaphragm at its sig ting end, ashutter, and an intermediate translucent diaphragm having an opaque mark thereon. 3. In a device for determinin photo'- graphic exposures, a tube or casing aving a transparent colored diaphra m, a shutter at" its light inlet end, -means or opening and desired extent,

openin an opaque mark th o aque mark between said transparent diap agIm and the shutter. V I

4. n a device for determinin photographic exposures, a. tube or casing avin a transparent colored diaphragm at its sig ting end, a shutter at its light inlet end, a

translucent diaphragm intermediate the ends' of the casing, and means for openin and closing the shutter, the said trans ucent diaphragm having an opaque mark thereon.

5. In a device for determinin photographic exposures, a tube or casing avin a transparent colored diaphragm at its sig ting end, a shutter at the other end, a translucent diaphragm intermediate the ends of the casing, and means for o ening and closing the shutter, the said trans ucent diaphragm havin an opaque diametrical line thereon.

6. n a device for determining photographic exposures, the combination with a tube or casing, of a shutter arranged at the light inlet end thereof, a slidable wed e for the shutter, an index and sea e for indicating the degree of opening of the shutter, a translucent diaphragm arranged in the .rear of the shutter and a colored transparent diaphragm between said translucent diaphragm, and the sighting end of the tube or casing the said translucent diaphragm having ereon,

' In testimony whereof I affix my signature 7 Y in presence of two witnesses.

JOSEPH P. MEYER. Witnesses:

J. A. WA'rsoN,

Anrnun L. BRYANT. 

